Stock-Based Compensation and Employee Benefit Plans - Summary of the Activity under the 2000 Plan (Detail) - 2000 Plan, Vicor [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Options Outstanding, Beginning balance	1,696,222
Options Outstanding, Granted	96,322
Options Outstanding, Forfeited and expired	(25,087)
Options Outstanding, Exercised	(401,540)
Options Outstanding, Ending balance	1,365,917
Options Outstanding, Exercisable	707,244	730,388	565,861
Options Outstanding, Vested or expected to vest	1,332,671
Weighted Average Exercise Price, Beginning balance	$ 8.82
Weighted Average Exercise Price, Granted	18.41
Weighted Average Exercise Price, Forfeited and expired	10.92
Weighted Average Exercise Price, Exercised	8.21
Weighted Average Exercise Price, Ending balance	9.63
Weighted Average Exercise Price, Exercisable	8.01	$ 7.74	$ 7.24
Weighted Average Exercise Price, Vested or expected to vest	$ 9.54
Weighted-Average Remaining Contractual Life in Years, Outstanding	6 years 2 months 16 days
Weighted-Average Remaining Contractual Life in Years, Exercisable	5 years 9 months 25 days
Weighted-Average Remaining Contractual Life in Years, Vested or expected to vest	6 years 2 months 8 days
Aggregate Intrinsic Value, Outstanding	$ 15,409
Aggregate Intrinsic Value, Exercisable	9,116
Aggregate Intrinsic Value, Vested or expected to vest	$ 15,161